The Experts below are selected from a list of 183 Experts worldwide ranked by ideXlab platform
M E Bartkow - One of the best experts on this subject based on the ideXlab platform.
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the occurrence of the herbicide Dalapon 2 2 dichloropropionate in potable water as a disinfection by product
Journal of Environmental Monitoring, 2011Co-Authors: Darryl William Hawker, Janet Cumming, A J Watkinson, M E BartkowAbstract:Salts of 2,2-dichloropropionic acid, such as Dalapon, are well known as herbicides and are regulated as such in potable water in Australia and elsewhere. It is also an identified disinfection by-product (DBP), but little is known about the compound's formation and typical levels from this source. This work presents results from a sampling campaign where 2,2-dichloropropionate was found at levels between 0.1 and 0.5 µg l−1 in potable water samples from a major treatment plant in South East Queensland, Australia. However, levels were below the reporting limit (0.01 µg l−1) in the immediate source water for the plant. Also, temporal trends in 2,2-dichloropropionate observed in treated water during sampling mirrored those of trihalomethanes albeit at much lower concentrations, suggesting that the occurrence is due to in situ formation as a DBP. This could present a regulatory dilemma in some jurisdictions.
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a screening level fate model of organic contaminants from advanced water treatment in a potable water supply reservoir
Water Research, 2011Co-Authors: Darryl William Hawker, Janet Louise Cumming, Peta A Neale, M E Bartkow, Beate I EscherAbstract:Augmentation of potable water sources by planned indirect potable reuse of wastewater is being widely considered to address growing water shortages. Environmental buffers such as lakes and dams may act as one of a series of barriers to potable water contamination stemming from micropollutants in wastewater. In South-East Queensland, Australia, current government policy is to begin indirect potable reuse of water from reverse osmosis equipped advanced water treatment plants (AWTPs) when the combined capacity of its major storages is at 40% capacity. A total of 15 organic contaminants including NDMA and bisphenol A have been publically reported as detected in recycled water from one of South-East Queensland's AWTPs, while another 98 chemicals were analysed for, but found to be below their detection limit. To assess the natural attenuation in Lake Wivenhoe, a Level III fugacity based evaluative fate model was constructed using the maximum concentrations of these contaminants detected as input data. A parallel aquivalence based model was constructed for those contaminants, such as dichloroacetic acid, Dalapon and triclopyr, which are ionised in the environment of Lake Wivenhoe. A total of 247 organic chemicals of interest, including disinfection by-products, pesticides, pharmaceuticals and personal care products, xenoestrogens and industrial chemicals, were evaluated with the model to assess their potential for natural attenuation. Out of the 15 detected chemicals, trihalomethanes are expected to volatilise with concentrations in the outflow from the dam approximately 400 times lower than influent from the AWTPs. Transformation processes in water are likely to be more significant for NDMA and pharmaceuticals such as salicylic acid and paracetamol as well as for caffeine and the herbicides Dalapon and triclopyr. For hydrophobic contaminants such as cholesterol and phenolic xenoestrogens such as 4-nonylphenol, 4-t-octylphenol and bisphenol A, equilibrium between water and sediments will not be attained and hence fate processes such as removal in outflow are predicted to become relatively important.
Fahrul Huyop - One of the best experts on this subject based on the ideXlab platform.
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identification of novel bacterial species capable of degrading Dalapon using 16s rrna sequencing
Jurnal Teknologi, 2016Co-Authors: Javad Hamzehalipour Almaki, Rozita Nasiri, Wong Tet Soon, Fahrul HuyopAbstract:2,2-dichloropropionic acid (2,2DCP) is used as herbicide in agricultural industry and it is one of the halogenated organic compounds distributed widely in the world causing contamination. In this study, a bacterial strain isolated from contaminated soil where halogenated pesticides applied in Universiti Teknologi Malaysia and it was named “JHA1”. Bacterium JHA1 was able to utilize 2,2 dichloropropionate 2,2-DCP or (Dalapon) as a source of carbon and energy. Based on 16S rRNA analysis, the isolate showed 87% identity to Terrabacter terrae strain PPLB. The identity score was lower than 98% so that it was suggested to be new organisms that worth for further investigations if it will be proven that this is novel. Therefore, current isolate was designated as Terrabacter terrae JHA1. The isolate grew in the minimal media containing 10 mM, 15 mM, 20 mM and 25 mM of 2,2- DCP as the sole energy and carbon source and the best growth rate was in 20 mM as the optimum concentration of 2,2-DCP while bacterial growth was inhibited in medium with 30 mM 2,2-DCP.
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molecular identification and characterization of Dalapon 2 2 dichloropropionate 2 2dcp degrading bacteria from a rubber estate agricultural area
African Journal of Microbiology Research, 2012Co-Authors: Wenyong Wong, Fahrul HuyopAbstract:The extensive use of herbicides in agricultural area over the past years resulted in environmental pollution. A total of 4 potential bacterial strains were isolated from the rubber estate using minimal media containing 2, 2-dichloropropionate (2, 2-DCP) as sole source of carbon and energy. The 16S rDNA analysis was carried out for genus identification study. Phylogenetic analysis suggested that strains D1, D6 and D9 were closely related with Enterobacter cloacae ATTC13047, whereas, strain Dw was closely related with Burkholderia sp. KU-25 with distance values of 0.001 and 0.004 base substitutions per site, respectively. Since strains D1, D6 and D9 belong to the same genus, therefore, D9 and Dw were further analysed. The growth profiles of both D9 and Dw in minimal liquid medium containing 40, 20 and 10 mM 2,2-DCP were studied. Strain Dw growth was approximately 3 times faster than D9. In conclusion, faster growth rate for strain Dw indicates the pragmatic application of the bacterial strains to degrade residual herbicide in the environment.
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degradation of millimolar concentration of the herbicide Dalapon 2 2 dichloropropionic acid by rhizobium sp isolated from soil
Biotechnology & Biotechnological Equipment, 2012Co-Authors: Fahrul Huyop, Ronald A CooperAbstract:The herbicide Dalapon is widely used in agricultural areas and is persistent in ground water. A Rhizobium sp. was able to grow at 0.2 mM 2,2-dichloropropionic acid (2,2DCP), which was 100-fold lower than the concentration of the substrate routinely used. Apparently, no new dehalogenases are required to allow growth on this low concentration of 2,2DCP as judged by electrophoretic mobility of dehalogenase proteins in native-PAGE analysis and protein separation by anion-exchange column chromatography. The kinetic analysis suggested that the known dehalogenases were able to act efficiently on low concentrations of haloalkanoic acids. The amount of each dehalogenase, from cells grown on low substrate concentration was different compared to that seen at 20 mM 2,2DCP due to complex regulatory controls, which respond to the growth environment.
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molecular prediction of dehalogenase producing microorganism using 16s rdna analysis of 2 2 dichloropropionate Dalapon degrading bacterium isolated from volcanic soil
Journal of Biological Sciences, 2010Co-Authors: Azzmer Azzar Abdul Hamid, Sinin Hamdan, Shahrul Hisham Zainal Ariffin, Fahrul HuyopAbstract:A phylogenetic analysis of an unknown strain AZZ2 isolated from volcanic area Gunung Sibayak Indonesia was performed. Their phylogenetic relationships were analysed using MEGA4 software® to ascertain its evolutionary distance by reconstructing a phylogenetic tree of these organisms. The evolutionary history and bootstrap consensus tree were inferred using the Neighbor-Joining method from 500 replicates. The tree is drawn to scale, with branch lengths (next to the branches) in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the p-distance method and were in the units of the number of base substitutions per site. Based on the partial 16S rDNA sequence determination, the strain showed high sequence similarity to Citrobacter sp. strain JC73/SL7. AZZ2 gene was also compared among known dehalogenase producing bacteria 16S rDNA genes. The results suggested that AZZ2 was closely related to the Serratia marcescens HL1. On the basis of phylogenetic identification only, AZZ2 was subjected to grow on 2,2-dichloropropionate (2,2DCP). The results suggested that strain AZZ2 can degrade 2,2DCP as expected similar to the characteristic of strain HL1 that can grow on halogenated compound. From this study, there was a possibility to predict the phenotype of newly isolated bacteria. The present findings also show that the evolutionary relationships of 16S rDNA gene strain AZZ2 were illustrated by phylograms and both topology are not in good agreement and may suggest an uncertainty of the origin of dehalogenases in volcanic area.
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dehalogenase from methylobacterium sp hj1 induced by the herbicide 2 2 dichloropropionate Dalapon
African Journal of Microbiology Research, 2008Co-Authors: Ng Hong Jing, Aishah Mohd Taha, Rolando V Pakingking, Roswanira Abdul Wahab, Fahrul HuyopAbstract:Heavy industrial activities and agricultural processes require consumption of many halogenated compounds, and release them continuously as pollutants into the environment. These xenobiotics show high toxicity and persistence and cause many problems to the society, soils and ground water. Microbial dehalogenases are involved in the biodegradation of many important chlorinated compounds. A bacterial strain identified as Methylobacterium sp. HJ1 is able to degrade the herbicide 2,2-dichloropropionic acid by removal of the halogen and subsequent metabolism of the product for energy. D, L-2-chloropropionate also supported good growth of the organism but 3-chloropropionate, monochloroacetate and dichloroacetate were not utilized. Cell-free extracts of the 2,2-dichloropropionate-grown bacteria converted 2,2-dichloropropionate into pyruvate with the release of two chloride ions for each molecule of pyruvate formed. This indicates the presence of dehalogenase activity in the cell-free extracts. Only 2,2-dichloropropionate and D, L-2-chloropropionate were inducers and substrates for the dehalogenase. Monochloroacetate and dichloroacetate did not serve as an inducer, whereas 3-chloropropionate was a non-substrate inducer.
Darryl William Hawker - One of the best experts on this subject based on the ideXlab platform.
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the occurrence of the herbicide Dalapon 2 2 dichloropropionate in potable water as a disinfection by product
Journal of Environmental Monitoring, 2011Co-Authors: Darryl William Hawker, Janet Cumming, A J Watkinson, M E BartkowAbstract:Salts of 2,2-dichloropropionic acid, such as Dalapon, are well known as herbicides and are regulated as such in potable water in Australia and elsewhere. It is also an identified disinfection by-product (DBP), but little is known about the compound's formation and typical levels from this source. This work presents results from a sampling campaign where 2,2-dichloropropionate was found at levels between 0.1 and 0.5 µg l−1 in potable water samples from a major treatment plant in South East Queensland, Australia. However, levels were below the reporting limit (0.01 µg l−1) in the immediate source water for the plant. Also, temporal trends in 2,2-dichloropropionate observed in treated water during sampling mirrored those of trihalomethanes albeit at much lower concentrations, suggesting that the occurrence is due to in situ formation as a DBP. This could present a regulatory dilemma in some jurisdictions.
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a screening level fate model of organic contaminants from advanced water treatment in a potable water supply reservoir
Water Research, 2011Co-Authors: Darryl William Hawker, Janet Louise Cumming, Peta A Neale, M E Bartkow, Beate I EscherAbstract:Augmentation of potable water sources by planned indirect potable reuse of wastewater is being widely considered to address growing water shortages. Environmental buffers such as lakes and dams may act as one of a series of barriers to potable water contamination stemming from micropollutants in wastewater. In South-East Queensland, Australia, current government policy is to begin indirect potable reuse of water from reverse osmosis equipped advanced water treatment plants (AWTPs) when the combined capacity of its major storages is at 40% capacity. A total of 15 organic contaminants including NDMA and bisphenol A have been publically reported as detected in recycled water from one of South-East Queensland's AWTPs, while another 98 chemicals were analysed for, but found to be below their detection limit. To assess the natural attenuation in Lake Wivenhoe, a Level III fugacity based evaluative fate model was constructed using the maximum concentrations of these contaminants detected as input data. A parallel aquivalence based model was constructed for those contaminants, such as dichloroacetic acid, Dalapon and triclopyr, which are ionised in the environment of Lake Wivenhoe. A total of 247 organic chemicals of interest, including disinfection by-products, pesticides, pharmaceuticals and personal care products, xenoestrogens and industrial chemicals, were evaluated with the model to assess their potential for natural attenuation. Out of the 15 detected chemicals, trihalomethanes are expected to volatilise with concentrations in the outflow from the dam approximately 400 times lower than influent from the AWTPs. Transformation processes in water are likely to be more significant for NDMA and pharmaceuticals such as salicylic acid and paracetamol as well as for caffeine and the herbicides Dalapon and triclopyr. For hydrophobic contaminants such as cholesterol and phenolic xenoestrogens such as 4-nonylphenol, 4-t-octylphenol and bisphenol A, equilibrium between water and sediments will not be attained and hence fate processes such as removal in outflow are predicted to become relatively important.
Gilbert Schwerdtfeger - One of the best experts on this subject based on the ideXlab platform.
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improvement in low temperature resistance of sugar beet and garden beet seedlings treated with sodium tca and Dalapon
Canadian Journal of Agricultural Science, 2016Co-Authors: William G Corns, Gilbert SchwerdtfegerAbstract:Sugar-beet and garden-beet seedlings were grown in darkness and high humidity for 6 days at approximately 21.5°C. in Petri dishes containing vermiculite moistened with a standard volume of water or with 4 to 8 p.p m active concentration of TCA (sodium salt of tricholoroacetic acid) or of Dalapon (sodium salt of 2,2-dichloropropionic acid). Shoots were then cut off and attached basally to horizontal bands of Scotch tape on a wire frame and rotated slowly during controlled exposures to −10°C. for periods of 5 to 10 minutes. Such treatments revealed highly significant improvement in cold resistance of chemically treated seedlings as judged by numbers of seedlings surviving their exposures in the freezer.
Shane A Snyder - One of the best experts on this subject based on the ideXlab platform.
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analysis of haloacetic acids bromate and Dalapon in natural waters by ion chromatography tandem mass spectrometry
Journal of Chromatography A, 2017Co-Authors: Tarun Anumol, Jay Gandhi, Shane A SnyderAbstract:The addition of oxidants for disinfecting water can lead to the formation of potentially carcinogenic compounds referred to as disinfection byproducts (DBPs). Haloacetic acids (HAAs) are one of the most widely detected DBPs in US water utilities and some of them are regulated by the US Environmental Protection Agency (USEPA). The present study developed a method to analyze all the compounds in the USEPA method 557 (nine HAAs, bromate and Dalapon) plus four potentially more toxic iodinated HAAs in water by coupling ion chromatography with tandem mass spectrometry (IC-MS/MS). This aqueous direct injection method has significant advantages over traditional GC methods, which require a derivatization and sample extraction that are laborious, time-consuming, and can negatively impact reproducibility. The method developed in this study requires half the time of the current USEPA method 557 on IC-MS/MS while including more compounds and achieving sub-μg/L level method detection limits (MDLs) for all 15 target analytes. The single laboratory lowest concentration minimum reporting level (LCMRL) has also been determined in reagent water, which ranged from 0.011 to 0.62μg/L for the analytes. The mean recoveries of the analytes during matrix spike recovery tests were 77-125% in finished drinking water and 81-112% in surface water. This method was then applied to untreated, chlorinated, and chloraminated groundwater and surface water samples. Bromate and 9 HAAs were detected at different levels in some of these samples.
